Photoflash synchronizing mechanism



G. N. SMITH PHOTOFLASH SYNCHRONIZING MECHANISM Oct. 6, 1953 7 sheetssheet 1 Original Filed June 16, 1947 INVENTOR. GORDON N. SMITH W M 7 7 Ur' H 9 5 Oct. 6, 1953 cs. N. SMITH PHOTOFLASH SYNCHRONIZING MECHANISM 7Sheets-Sheet 2 Original Filed June 16, 1947 INVENTOR. GORDON N. SMITH WNK G. N. SMITH PHOTOFLASH SYNCHRONIZING MECHANISM Oct. 6, 1953 7 sheets'sheet 3 Original Filed June 16, 1947 INVENTOR.

O 953 I e. N. SMITH 2,554,299

PHOTOFLASH SYN CHRON IZING MECHANISM Original Filed June 16, 1947 7Sheets-Sheet 4 INVENTOR. Gordon N. smifh Oct. 6, 1953 e. N. SMITHPHOTOFLASH SYNCHRONIZING MECHANISM 7 Sheets-Sheet 5 Original Filed June16, 1947 nhN Nu N

INVENTOR. GORDON N. SMITH BY Mum Oct. 6, 1953 e. N. SMITH PHOTOFLASHSYNCHRONIZING MECHANISM 7 Sheets-Sheet 7 Original Filed June 16, 1947INVENTOR. Cora on /V. 5/121? QWMW Patented Oct. 6, 1953 PHOTOF'LASHSYNCHRONIZING MECHANISM Gordon N. Smith, Portland, Oreg.,

assignor, by

mesne assignments, to Sawyers Inc., Progress, reg., a corporation ofOregon Original application 15, 1951. 14, 1950, Serial No.

2 Claims.

The present invention relates to the art of photography and has to dowith various refinements and improvements in operating mechanismsforming portions of a highly adaptable camera. The present applicationdiscloses a stereoscopic camera having a pair of lenses, but it will beappreciated from the following description that portions of the hereindisclosed invention may be utilized in a camera having a single set oflenses for taking ordinary pictures. The camera is distinguished byhaving shutter mechanism and means to select the exposure speed thereofwhich may be set so as to take exposures at a fixed high speed, atselectable intermediate speeds, at a fixed slow speed, or to permit thetaking of manually controlled time exposures. It is to be appreciatedthat the present invention may be utilized in cameras of other types,but in order to illustrate and explain the operation of the presentinvention it is set forth in a camera of the above type as an example ofan operative association.

This application is a division of my copending application Serial No.754,961, filed June 16, 1947, now Patent No. 2,553,015, issued May 15,1951.

The principal object of the present invention is to provide meanswhereby a shutter timing mechanism as discussed above is coupled to aphotoflash mechanism in such manner as to insure accuratesynchronization of the switch and shutter blades for proper photofiashoperation.

Another object of the present invention is to couple a shutter timer andsynchro-switch in such a manner that the operation of the shutterrelease mechanism b the operator has no effect on the switchsynchronization, thus eliminating the necessity for the photographerlearning to maintain uniform actuation of the shutter release button.

Another object of the present invention is to design a photoflash switchsynchronizing mechanism in such manner as to eliminate the use ofpigtails for conducting the current.

A further object of the present invention is to maintain a commonstarting position for a shutter blade timer mechanism regardless of thetime interval adjustment in order to simplify synchroswitch coupling,and to insure maximum driving tension from the escapement spring.

Another object of the present invention is to combine a shutter camerawith a photo-flash switch so as to close the switch a preselected timeinterval before the opening of the light apertures for film exposure,and to open the switch after June 16, 1947, Serial No. 754,961, nowPatent No.

Divided and 2,553,015, dated May this application July 2 the exposure topermit safe replacement of a flash bulb.

Another object of the present invention is to combine one contact bladeof a synchro-switch with the escapement mechanism in such manner thatthe spring tension of the contact blade helps accelerate the escapementas the shutter is tripped, but will be expended before actual opening ofthe shutter in order to preserve the shutter timing calibration.

The foregoing and other objects and advantages of the present inventionwill be more readily understood from inspection of the accompanyingdrawing taken in connection with the 'following specification, whereinlike numerals refer to like parts throughout.

Fig. 1 is a partially schematic view of the major portion of the shutterrelease and timing mechanism of the camera in set position. It is to beappreciated that various portions of this mechanism overlap but occupyvarious levels, hence some portions are drawn in skeleton outline;

Fig. 2 is a view illustrating the major portion of the shutter releaseand timing mechanism just after being released for taking a high speedexposure;

Fig. 3 illustrates the shutter release and timing mechanism just afterbeing released to take an exposure of the longest possible adjustableduration or at the slowest fixed speed.

Fig. 4 illustrates the shutter release and timing mechanism whenreleased to take a time exposure, the parts being illustrated as theywould appear corresponding to the bulb open position of a standardcamera;

Fig. 5 illustrates the shutter release and timing mechanism at thetermination of a time exposure with the parts in the position they wouldassume corresponding to the bulb closed position of a standard camera;

Fig. 6 is a partial vertical section taken substantially from the planeindicated by the line 6-6 (center of Fig. 1) illustrating the exposuretime selecting mechanism, selecting knob and eX- posure speed dial;

Fig. '7 is a partial horizontal section taken substantially along line7-1 of Fig. 6;

Fig. 8 is a plan view of the escapement mechanism with the timer camsillustrated in dash line for the purpose of clarity;

Fig. 9 is a plan view looking down upon the trip mechanism, along line9-9 of Fig. 10, with all other parts eliminated for clarity;

Fig. is an end elevation taken from the plane I-IG of Fi 9;

Fig. 11 is a plan view illustrating the reset mechanism with the partsillustrated in the "set position corresponding to Fig. 1;

Fig. 12 is a rear view showing the shutter blades superimposed and. inthe positions they occupy at the end of a resetting movement;

Fig. 13 shows the shutter blades in the positions they occupy when thecamera is set;

Fig. 14 illustrates the shutter blades in the positions corresponding tothe commencement of a time exposure;

Fig. 15 illustrates the shutter blades in the positions they occupy atthe end of an exposure and prior to the operation of the resetmechanism;

Fig. 16 is a vertical section taken through the shutter blades and theshutter blade case substantially along the line I6I6 of Fig. 11;

Fig. 17 is a partial vertical section, on an enlarged scale, takensubstantially along line Il-I'I of Fig. 16;

Fig. 18 is a plan view of the synchro-switch with related mechanismshown in skeleton outline; and

Fig. 19 is a partial bottom view showing the synchro-switch adjustmentscrew.

Although all portions of the mechanism herein disclosed function inconjunction with each other various portions thereof will be separatelydescribed in order more clearly to describe the operation of the camera.These portions will be set aside under appropriate subtitles.

Shutter release and timing mechanism The shutter releasing and timingmechanism is mounted upon and between a pair of plates, the bottom plateE5 of the camera and an intermediate plate MS. The plate I43 is mountedupon a plurality of bosses IEQ extending upward from the bottom plate15, so that there is a space between the plates. A primary shutter latch9 is mounted on the upper surface of plate I43 and a secondary shutterlatch I0 is mounted on the lower surface of plate I43. The latchesextend beyond the plate a sufficient distance to engage in slots I69 andI5! (Fig. 12) of the front and rear shutter blades. The shutter consistsof a pair of shutter blades I and 3 movable from left to right byshutter blade springs 2 and 4 respectively (Fig. 16). When the shutterblades are set at the left of their travel the latch 9 holds them inthis position, at which position apertures I36 in the rear blade 3 arealigned with the lenses, but light is prevented from reaching the filmby the blade i whose apertures I35 are to the left of the lenses and notin line with them. The latch IE) is normally locked by the latch pawl IIwhich is also pivoted beneath plate I43. The shutter blade I never bearsagainst latch I0, and blade 3 normally does not bear against latch I9,which is a secondary latch or a timing latch. Latch i0 is released fromlatch pawl II through the operation of a main lever 8 (Figs. 1 to 5)which may be unintentionally moved due to impact or inertia effect, thuscausing the secondary latch pawl H to move out of engagement with thesecondary latch I0, but as soon as such a transient phenomenon hasceased the latch I9 is again retained by the latch pawl II. A lightspring 1139 holds latch iii in a counterclockwise direction to beengageable by pawl II. Latch 9 normally holds both shutter blades I and3. Latch 9 is also lightly urged counterclockwi e y a spring I38. Whenlatch 9 is released, as will presently appear, the stronger spring 2operating upon the blade I causes latch 9 tobe moved in a clockwisedirection to release blade I, which thereupon moves so as to bring itsapertures I35 in line with the lenses, and since the apertures I36 inblade 3 are in line with the lenses light is permitted to reach thefilm. Latch It has now engaged blade 3 due to its having been releasedby latch 9 and moving slightly to the right. Latch ID will be releasedat a later period, as will appear, so as to cause the apertures I36 tomove to the right beyond the lenses, thus cutting off the light from thefilm. It may be seen that the timing of releasing latches 9 and I9 timesthe exposure of the film.

The latch 9 is retained in latching position by a hook 200 on a primarylatch pawl I3 5 which is pivoted for convenience on a timing cam shaft19. The primary latch pawl I34 extends toward the right end of plate I43and carries a lever drive pin 46 at its right end which extends downwardthrough an irregularly shaped opening Zill in the plate M3. The primarylatch pawl E33 also extends toward the left end of plate I43 and isprovided with an offset extension which carries a primary latch pawlreset stud 3?. When the primary latch pawl E34 moves counterclockwiseabout its pivot 49, the hook 269 moves out of engagement with the latch9 to permit the shutter blade I to snap toward the right.

The latch pawl I34 is retained in the position illustrated in Fig. 1,which is in set position, meaning that the camera is set to (take apicture. In this position its right end is engaged by the downwardlyturned end of a release lever pawl I3 pivoted on a release lever pivot292 mounted on plate I43. The release lever pawl is provided with adownwardly turned tab 283 which engages a shoulder on a release lever l6extending toward the right of the plate I43 and pivoted at 292.

The left end of lever I9 extends over plate M3 and has a tab 204 passingthrough a hole 2&5 in the plate MB. A release lever spring I57 tends tohold the release lever in the position illustrated in Fig. 1. When thelever I5 is shifted clockwise to the position shown in Fig. 2 theshoulder thereon engaging the tab 233 rocks the release lever pawl 53from engagement with the end of primary latch pawl I3 3. A strong springM having one end embracing a stud 29? on plate 53 is tensioned abouttiming cam shaft 59 and hooked around the lever drive pin 45 on theprimary latch pawl 13%. When the release lever I5 is thus moved out ofthe way the spring it moves the primary latch pawl I34 in acounterclockwise direction. After it moves far enough the hook ass isdisengaged from the latch 9 and the shutter blade snaps to the right. Itis to be appreciated that, since the shutter blades are not shown inFigs. 2 to 5 inclusive, the latches 9 or It, as the case may be, are notcorrectly illustrated in some cases since they should be rockedclockwise by the shutter blades. The reason for illustrating the latchesas shown is to emphasize the timing action of the release mechanism.

In order to release the secondary latch It means are provided to rockthe secondary latch pawl II counterclockwise about its pivot against thetension of a spring 346. Such means comprises a hook provided on thelower surface of the left end extension 2 ii) of main lever 8 whichnormally bears lightly against the end of latch pawl II or may floatadjacent thereto. The left end 2 I9 is twisted to lie in a verticalplane, so that II it:bears against the edge ofplate I43. The lever 8 isa floating lever not having .any ,fixed pivot. It is mounted beneath theplate I 43 and is pivotedzto the primary release pawl I34 by means ofthe lever drive pin 46 extending through the plate clearance hole 28!.

Motion of pawl I34 and main lever 8 is transmitted to the escapement bya main lever slot I48 engaging a sector gear stud 25 mounted'upon andprojecting upwardly from a sector gear 24 carried by a sector gear pivotI4! journaled in the two plates -I Sand I 43.

The other mechanism for controlling'the manner of movement of the mainlever 8 comprises a timing cam 48 splined to the timing cam shaft 49.The timing cam has 'a major radius portion I50 (Rig. '7) extending for afew degrees. This is followed by a slight step l-5I which marks thecommencement of a spiral surface I52, extending after releasing pawl forsubstantially three-fourths of the periphery of the cam. This isfollowed by afurther step leading to a minor radius I58 extending for afew degrees, the points of minor andmajorradius being joined by astraight surface. The relative position of cam 48 may be fixed byrotating the shaft 49, the desired location thereof being indicated by adial as will presently appear.

The sector stud 25 engaged in slot I43 acts to translate the relativelylinear motion of slot I478 to rotary motion of the sector gear 24. In sodoing the movement of the right end of main lever 8 is retarded due tothe drag of an escapement mechanism driven by the sector gear 24. Thestud 25 and slot I48 may be called a flexible coupling. The direction ofmovement of any portion of main lever 8 is determined by the movement ofpin 48 and the adjustment of cam 48, but the time interval betweenrelease of latches .9 and I8 is determined by the speed of movement ofsector gear 24 and the setting of cam 48.

When the major radius portion I58 ,of cam 48 is positioned at a desiredpoint, such as illustrated in Fig. 2, it is in position to engage a mainlever fulcrum I49 provided on the main lever B. In this position releaseof the primary latch pawl I34 and slight counterclockwise movement ofthe primary latch pawl causes release of the secondary latch I9 prior torelease of the primary latch 9. This is brought about as follows:

The spring I4 urges the pin 46 counterclockwise. Due to the retardingaction of the stud 25 in slot I48 the left end of lever 8 is rocked upuntil main lever fulcrum I49 contacts the cam portion I50. Slightcounterclockwise rotation of pawl I34 rocks the main lever 3 about itsfulcrum I49 to cause the extension 2I8 to strike pawl II and releaselatch I9 due to the force of spring I4 being greater than that of springI45. Thus, with this adjustment of cam 48, the latch I8 never holdseither shutter blade. The timing of the mechanism is such that releasepawl I I clears the latch I8 slightly before the hook 289 clears thelatch 9. As soon as the hook 289 clears latch 9 the springs 2 and 4cause movement of the shutter blades I and 3 since neither latchrestrains them. The springs 2 and 4 are of substantially equal strengthand operate against substantially equal load so that the shutter bladesI and 3 move at substantially equal speeds across the lenses. Theexposure will, therefore, be very fast inasmuch as the apertures I35 andIce flash past the lenses, the extent of exposure being controlledentirely by the overlapping of the apertures as they move past thelenses (Fig. 13).

I extension 2w against pawl II When the cam '48 isrotated to a slightextent counterclockwise fromthe position shown-in Fig. 2:the beginningof the spiral I52 is presented for engagement with the fulcrum I49. Insuch case the movement of mainlever 8 to contact the release pawl II andrelease thesecondary latch I II occurs after the hook 200 has releasedthe primary latch 9. This is due to the delayed engagement of thefulcrum I49 and the cam face I52 which permits the lever 8 to rock aboutfulcrum I49 and contact secondary latch pawl II only after hook 208 hasreleased primary latch 9. The motion of main lever 8 is retarded by thesector gear stud 25 engaging the main lever slot I48, said pin rotatingthe sector gear 24 and its pivot I4! and driving a ratchet 230 through aratchet pinion 28 (as will be explained later). The ratchet mechanismprovides means for slowing the movement of the sector gear so that aninterval of time is provided between the release of latch 9 and therelease of latch I ii. The radius of cam 48 at this position is such asto permit the hook 280 to release latch 9 before the lever extension 2IDstrikes release pawl II to release latch I8. Thus the latch 9 releasesboth blades, blade I continuing to its end position where its aperturesuncover the lenses, blade 3 moving first into contact with latch I0,then after a time interval moving to its end position. The exposure timeinterval may be increased to a maximum continuously adjustable positionalmost to the limit of the spiral I52.

When the cam 48 has been rotated to the position illustrated in Fig. 3,a notch 234 in a long interval cam 47 splined to shaft 49 is broughtinto alignment with a cam follower end 233 on a long interval lever 28(Figs. 6, '7, 8). As will be explained later, this action brings a longinterval pawl 29 into engagement with the ratchet 238 in addition to anescapement pawl 21 which normally engages the ratchet 230. Thus gear 24must overcome the slowing effect of the two pawls 21 and 29 as the lever8 is driven by spring I4 through pin 46 from its set position to aposition where its fulcrum I49 bears against the cam 48 to cause theextension 2I0 to release the secondary latch I8. When the cam 48 is inthis position at the smallest end of the spiral I52 a long interval offixed duration elapses between the release of shutter blade I and therelease of shutter blade 3.

When the cam 43 is rotated to the position shown in Fig. 4 the minorradius is pre sented to the fulcrum M9, this minor radius being suchthat the lever 8 never comes to bear against cam 48 and movement of thesector gear 24 is arrested by the gear 24 striking a boss I54 before anytension can be brought to bear by to release the secondary latch I9.This condition will remain static as long as the release lever I5 isheld in its depressed position. This position corresponds to the bulbposition of a camera and continues as long as the lever I8 is helddepressed. Upon release of the lever I5 spring I57 causes the lever IEto move counterclockwise. The lever 8 is floating in a position suchthat a main lever stud I58 thereon is near the upper end of a slot 2! 5in the plate 243 and is in position to be struck by the tail es of leverI8 (Fig. 5). The movement of the lever 8 through this medium issuilicient to cause the extension 2H3 to release the secondary latch I9and cause the blade 3 to end the time exposure, this actioncorresponding to the closing of a camera shutter by a bulb time exposuremechanism.

I thus have, through the same sets of parts, means for instantaneousexposure, means for infinitely variable fast exposure, means for a set,long exposure, and means for a manually controllable time exposure oflengthy extent.

Exposure speed adjustment Figs. 6 and '7 show the arrangement of thecams 6? and t8, the shaft es and a lrnob iii together with an exposurespeed dial Hi. It will be seen from Fig. '7 that the extreme lower endof shaft d9 rests in a cavity 22%; in the bottom plate iii and its upperend passes through a suitable opening in the top plate 22! of thecamera. The lower end of the shaft is spiined to receive came 4? and t3and hold them against relative rotation with respect to each other andthe shaft it. A collar 222 is mounted on the shaft to hold the camsagainst endwise movement against the thrust of a friction washer i 15which tends to hold the assembly in its adjusted position. Immediatelyabove the washer lit the shaft is provided with a step enlargement whichis journaled in an opening in the mounting plate hi3. Immediatelythereabove the shaft is provided with a second step that journals theprimary latch pawl 113%, which is retained in posi tion by a third stepin the shaft. The upper end of the shaft carries a hub 223 which isfastened to the shaft by a set screw 2%, and the dial i ii is fixed tothe upper surface of the hub 223. The periphery of the dial carri sfigures and indicia on its upper surface which are visible through thearcuate window Hi l. The upper end of the shaft, after passing throughthe top plate 22 l is keyed to enter a key socket in knob hi2 hlCh isretained in position by a screw 22" threaded into the end of the shaft.Rotation of the knob hi2, therefore, rotates cams audit, and the extentof rotation thereof is indicated by the dial indicia passing a suitableindex point (not shown) on the up, er surface of the plate 225. Theindicia carried on the dial Mi indicate the fraction of second ofexposure, or other information relating to the exposure speed.

Escapement mechanism Fig. 8 further relates to the mechanism closed inFigs. 3. to '7 inclusive in that it discloses the complete escapementmechanism including the sector gear 2%. In this figure, for clarity ofillustration, the mounting plate its and the cams 3? and f; shown indash outline. it will be seen that the sector gear 25 engages with theratchet pinion 25 which is fastened to the upper surface and concentricwith the escapeinent ratchet When the portion of cam including the majorradius and all but the minor radius is in position to engage the fulcrumi iii oi the main lever only one of two ratchet escapement pawls isengaging the teeth of the ratchet 253 to slow the movement of the sectorgear 25. This primary escapement pawl is indicated by the numeral El. -tmay be seen that the teeth thereof engage the teeth of the ratchet andpermit their release in time steps rather than in a continuousuninterrupted movement. This type of escapement well known in the art.

When the cams it and 3? are turn-ed to permit the fulcrum point its oflever B to engage the earn it at a radius out slightly larger than the8. smallest radius portion of the spiral 552 the exposure is at amaximum time exposure of fixed duration with the shutter closingautomatically at the end of the time. This is accomplished by mechanismdisclosed in Fig. 8 in the position disclosed in Fig. 8. It will be seenthat the long interval escapement pawl 29 is pivoted at 232 beneath onearm of the long interval lever 28 which is pivoted on a boss in plate l5and secured with a screw 232 threaded into the mounting boss. The farend of the long arm of lever 28 is provided with a cam follower end 233which is adapted to engage the long interval notch 23A in cam 51. Thusthe long interval escapement pawl 29 is brought into engagement with theteeth of the ratchet gear 238 by a tension spring 253 extending betweenthe crank arm of lever 28 and a boss 236 extending upward from thebottom plate it. The arm 235 is urged against an eccentric screw tilt,which may be rotated to adjust the engagement of pawl with ratchet 23@.The ratchet gear 2353 now has to overcome the inertia of the pair pawls2i and 29 rather than the single pawl 27 during the movement of thesector gear 2%.

When the shaft .9 is rotated in either direction from this position thelong interval escapement pawl 29 is removed from engagement with theteeth of the ratchet gear 23c and the ratchet gear has to overcome theinertia of the pawl 2i only, therefore the length of time required forthe main lever S to pivot about the cam ts is controlled entirely by thesingle escapement pawl In this position the back of pawl 2i} engages apair of bosses 23? preventing the pawl from rocking into engagement withthe ratchet 238.

Trip mechanism and projects above an opening in an extension of the topplate 22! indicated by the numeral 2453. The button I33 is provided witha flange 24E limiting outward movement of the button. A button guide pin242 extends downward into an opening in a boss 243 rising upward fromthe bottom plate I5. The pin 2&2 passes through an opening in the shortarm of a trip lever 2 54 which is mounted upon a pivot 245 pressed intothe frame of the camera. The button 133 rests upon the horizontal shortarm of lever 2:36, which is normally restrained in its uppermostposition by the spring I5! engaging the tail of lever It (Fig. 1). Thelong right end of lever is is provided with a rounded knoblikeprojection 256 which engages the lower extremity of the vertical longarm 24%? of the trip lever. A screw 248 is threaded into the portion 2stof the top plate and is removable to permit the attachment of a standardrelease cable. counterclockwise rota tion of trip lever 254 is limitedby the interference of shutter case plate 5 with arm 2M. It may be seenfrom the foregoing and the descriptron of the mechanism in Figs. 1 to 8inclusive that when an accurately fast exposure is desired the buttonIE3 is depressed, which action will cause release of both the shutterblades. When a manually controlled time exposure is desired the buttonI33 is depressed, but due to the inability of main lever 3 to releasethe secondary latch ill, the film will remain exposed to the light sagasiintil button I33 is released, whereupon spring I51 will cause lever I6to return to its set position and in so doing cause the tall 80 toengage the main lever stud I58 to release the secondary latch and endthe time exposure;

Reset mechanism The tab 203 is resting against the elbow of 'the'release lever I6. Theopposite face of; the tab 203 engages the tip of anarm 260 on a'reset stop pawl 15 which is pivoted at 26I to the cameraframe. A spring 18 is tensioned around the pivot 26! and has one plate262 of the camera and its opposite end hooked over the rear edge of thereset stop pawl pawl tab 263 into engagement with a reset cam notch I30provided in the surface of a cam II9 which is mounted upon a pivot 264extending upward from the bottom. plate I5. When the release lever I6 isrocked to the position illustrated in Fig. 2 the releaselever pawl I 3is rocked clockwise and the tab 203 rocks the reset stop pawl clockwiseto disengage it from the cam notch I30 against the tension of the spring18. The release lever pawl I3 is provided with a downwardly extendingtab 261 which engages an arcuate face 268 on the right end of primarylatch pawl I34 which is movingcounterclockwise. Therefore, as long asthe primary latch pawl is released the reset stop, pawl 15 cannotre-enga'ge the reset cam notch I30.

The reset cam IE9 is fixed to a large reset gear 19 which meshes with amounted upon a shaft 33 extending from the bottom plate I5 through thetop cover and which has fixed thereto a reset knob 40 (not shown). Thereset knob may now be turned counterclockwise and the resetting of theshutter mechanism will be accomplished in one complete revolution of thereset gear 19.

In Fig. I project through a'slot 210 The rear shutter case plate is aslot 21I, the lower edge of which is pressed end engaged against therear' small reset gear 36 11 it will be seen that the latches 9 and,

pawl 15 to bear ward from'the'face of gear 19. When the camera is setlever 35 occupies the position illustrated in'Fig'n. a 7 a The slots I60and 164 in' the shutter blades, as will presently appear a're of suchlength that I f .the exposure the left ends of the'slo'tsin the shutterblades are closely adjacent the finger 214'on the reset crank. As soonas. the exposure is completed, the release lever I '6 is'retur'ned' toits initial position, as indicated in Figl ll} permitting the tab 261 ofrelease lever pawl'l3 to bear against the face ZBB of pawl I34 byactioriof a spring 250 hooked over a tab 25I on lever I6, teiisionedaround the hub of pawl I3, and hooked over the edge of pawl I3. readies"the release lever V As will be the sector set posi- A reset crank offsetI46 engages the primary latch pawl reset stud 51 as the gear 19'completes substantially one-half of a revolution, whereupon additionalrotation of gear 19 engagement with the stud 51 but the pawl I34 isretained in fset positionv by the release lever pawl I3 which has beenmoved counterclockwise by spring 250. Spring 18 now brings reset stop Iagainst the face 216 of oam H9 which is of greater radius than the.bottom of the notch I30. The remaining semi-revolution of slot I60toward the left end, a short slot IBI near the center, and an edge slotI62 extending from the right of the center line toward the left end. Anend notch I6l is provided in the lower right corner. The rear shutterblade 3 is provided with a pair of apertures I36 having their right endsrounded and of the same radius as the rounded ends of apertures I35. Theapertures I36 are substantially rectangular beyond the rounded ends andare longer than apertures I35. A slot I64 is adapted to overlie the slotI66. A slot I67 is in horizontal alignment with the slot IEI and an edgeslot IE6 is in horizontal alignment with the slot I62. The upper rightcorner is provided with an end notch I68.

In Fig. 12 the blades I and 3 are shown in their relative position whenpushed by the reset lever 34 to the left end of the channel they occupybetween the blade case plates and 6. It will be seen that the finger 2Mon the reset lever has engaged the left ends of slots I69 and IE4 topush the blades completely to the left.

Tips of the latches 9 and Ill bear against the plates as the platesslide past them from right to left until the appropriate slots receivethem. The light spring I38 urges the latch S into the slots IBI andIii'i, and the light spring I39 urges the latch It into the slots I62and I66. This readies latch 9 for engagement by primary latch pawl I34and readies latch Ill for engagement by secondary latch pawl I I. Itwill be recalled that the offset I68 on reset lever 35 will nowreposition the pawl I34 and associated mechanism so that hook 200 willengage the tail of latch 9. Repositioning of primary latch pawl ltd willrock the main lever 8 clockwise to move its portion 2H away from thetail of latch pawl II permitting spring M6 to return the pawl I I intoengagement with latch I9.

As soon as the pin 275 passes beyond dead center and substantiallycoincidental with the latching just described the reset lever 35 startsto retract. It will be observed in Fig. 12 that latch 9 is positioned inthe left end of slot I6? which eifectively prevents movement of the rearblade 3 as urged to the right by its spring I. Latch 9 is at the rightend of slot IBI so that the front blade I may move toward the right asurged by its spring 2 until it engages latch 9 (Fig. 13). The blades aretherefore both held tensioned in the set position While the finger 2Mretracts t0 the far right end of the slots I60 and I56 as the reset camgear IQ completes its revolution to the position illustrated in Fig. 11.The blades are now in the set position with the camera lenses uncoveredby the apertures I36 but covered by blade I whose apertures I35 arestill to the left of the lenses. The blades are held in this position bylatch 9 and it will be noted (Fig. 13) that latch II) is slightly spacedfrom the left edge of slot I65 and is greatly spaced from the left edgeof slot I62. Latch IE! is preferably spaced about of an inch from theleft edge of slot I so that when the camera is set all of the bladerestraining force is provided by latch III which is held by positivelyretained mechanism including the pawl I3 and the pawl I3. Thus, ifshaking, or jarring, or dropping of the camera occurs to such an extentas to cause the main lever S, or other connected mechanism, to movesufficiently to release the secondary shutter latch pawl II, thesecondary latch IIl nevertheless remains in operating position and willbe re-engaged by the pawl II immediately after the transientdisturbance.

If an instantaneous high speed exposure is desired and the fulcrum pointits engages the major radius of the cam 58 to disengage the secondarylatch III prior to disengagement of the primary latch ,9, as soon aslatch 9 is released there will be nothing to restrain the blades againstmovement to'the right due to the effect of their springs (to bedisclosed later). The two blades, therefore, flash past the lenses andexpose the film at the highest speed possible, the duration of exposurebeing controlled by the length of the slots provided by the overlappingends of the apertures I35 and I36 and the fixed tension of the springs 2and I.

If, on the other hand, an exposure of fixed duration of adjustableextent is required and the cam 28 has been positioned to present itsspiral surface I52 to the fulcrum I49, the secondary latch II) will beretained until a variable length of time has elapsed after latch 9 hasbeen released. This action, illustrated in connection with Fig. 3, isfurther illustrated in connection with Fig. 14. It will be noted thatlatch 9 has been released first, thereby permitting the front blade I tospring entirely toward the right end of the camer until it is restrainedfrom further movement at which point the rounded ends of the aperturesI35 correspond with the rounded ends of the apertures 136 to provide acircular opening permitting the passage of light to the film. With therelease of latch 9 by pawl I3 5, the movement of blade I pivots latch flclockwise against the tension of its spring I38, and the tip of latch 9lightly presses against blade 5. Latch It, however, is still held by thelatch pawl I I and engages and prevents the rear blade 3 from movingmore than the distance necessary for the left edge of slot I86 to engagelatch It, as previously noted about of an inch. However, this slightmovement does not affect the light transmitted as the extended aperturesI36 require much more movement to enter the light path. Nor does thisslight movement affect the timing as the movement is concluded beforeblade I uncovers the lenses. The primary function achieved by holdingthe blade 3 with latch El and not by latch II), except when an exposurehas been initiated, is to provide a locked mechanism protected fromshock to insure dependable operation when it is initiated. Dependentupon the positioning of the spiral I52, an interval of time elapsesbefore latch Iil releases the rear blade 3. When blade 3 is released itsprings to the right to the position illustrated in Fig. 15, causing theapertures I36 to move beyond the apertures I35 and thus terminate theexposure. Movement of blade 3 rotates latch II clockwise against thetension of spring I39, and the tip of latch It presses lightly againstblade 3.

When a manually controlled time exposure is desired corresponding to theactions illustrated in Figs. 4 and 5, the primary latch 9 is firstreleased, as shown in Fig. 4, but due to the fulcrum I69 being oppositethe minor radius portion I58 in cam t8 the main lever 8 cannot releasethe secondary latch III. The blades will, therefore, rest in theposition illustrated in Fig. 14 as long as the release button I33 isheld depressed. When the button is relinquished release lever It yieldsto spring I5? and the portion at of the release lever It strikes themain lever stud, I58 to release the secondary latch I0 and complete theexposure.

7 Shutter blade pads and springs At the right'end of the slot betweenplates 5 and 6 there is provided a pair of pads of shockabsorbingmaterial, such as a pad formed of a; inch thick vellum paper. There is apad I59 adjacent the upper corners of the blades and a pad I10 adjacentthe lower corners of the blades (Fig. 15). It will be noted that theblade I has its end notch I51 in such position that the blade I isprevented from striking pad I10 and only strikes the upper pad I59.Similarly notch I68 in blade 3 causesblade 3 to strike the pad I10 only.This spacing of the pads and having them substantially independent ofeach other tends to eliminate the possibility ofv shutter bounce of suchan extent as to uncover the lenses after termination of the exposure. Ifthe two blades struck the same pad there would be the possibility of thetimed blows setting up sympathetic vibrations to such an extent as tobounce the rear shutter blade 3 back sumciently to uncover the lenses.

The blade I is provided with a wide slot I80 which has a narrowextension I8I at its top extending toward the left of the blade. At theshoulder formed at the beginning of the extension ISI there is provideda hole I82. The rear blade 3 has a slot I33 of substantially the samelength as slot I30 and a short extension H34v at its lower left corneradapted to overliev the hole I82 in blade I. Just above the extensionI84 there is a small hole I85. adapted to overlie the beginning of theextension- I8I in blade I.

Referring to Fig. 16 it will be seen that the front shutter blade caseplate 3 is provided with embossed ridge Iii? and a lower parallel ridgeI 38 which extend inwardly into the space between the case plates and 6.The rear plate 5 is provided with matching ridges I89 and I90respectively. The adjacent surfaces of the ridges define guides for theshutter blades I and 3. Below the lower guides there is a wide spaceprovided by stamping the plates outwardly and the slots I80 and I83 inthe shutter blades lie within this wide space. In Fig. 17 it will beseen that a tongue IN is stamped inwardly from plate 5, the tongue beingprovided with a pair of holes I92 vertically spaced the same distance asthe distance between the holes I32 and I85 in the shutter blades. Thespring 2 which operates the front shutter blade extends from hole I32 tothe lowermost hole I92 and the spring 4, which operates the rear shutterblade 3, extendsfrom hole I85 to the uppermost hole I 92. The springslie within the slots I80 and IE3 and do not bear against either shutterblade at any point except at their connecting ends. The ends of thesprings passing through the holes i822 and I35 extend into theextensions I33 and i8! respectively at certain periods of the shutteroperation. Fig. 17 illustrates the springs 2 and d extended as theywould appear when the shutter blades are in set position toward theleft. When blade I moves toward the right the hook on spring 4 is stillclear of the front blade due to the extension I8I.

There are thus provided operating springs of equal length which may beformed so as to have very nearly the same resiliency and which aretensioned to very nearly the same extent when the blades are set, andneither of which is subjected to frictional resistance by bearingagainst any other part. When the high speed, or fastest, exposure isdesired the two blades. are released simultaneously by the latch 9 andflash past the lenses, maintaining, because of the matched springs, theaperture slot seen in Fig. 12. When anadjustably longer exposure-isdesiredlatch I0 releases blade 3 at a timed interval after latch 9releases blade I. Therefore, the slot provided by the apertures iswider-or fully opened as determined by the setting of cam 48. In mostinstances the speed of the blades is sufficiently great to permit bladeI to complete its movement and come to rest before blade 3 starts tocover the lenses.

Synchro-switch In Fig. 1 it will be noticed that between the latch I0and the latch pawl II there is-an opening through the intermediate plateI43 through which a tab 32 projects to engage a shoulder I 59 on theprimary latch pawl I34. In Fig. 18 it-will be seen that this tab 32 ismounted on the free end of a short spring contact blade 3I. The springcontact blade 3I is retained by screws 300 against the side ofaprojection I rising from the bottom plate I5. Insulators 302 insulatethe witch blade (H from the screws 300 and the rear surface of the bladerests against a strip of insulating material 303. The strip 303 ismounted on the outer surface of a long switch blade 30 which is alsoinsulated from the screws 300 by the insulators 302. It in turn restsupon a strip of insulating material 304 positioned between it and theprojection 30I.

The lower end of the tab 32 is mounted to blade 3| by a silver contact305 which is in alignment with a silver contact 305 mounted on the longblade 30. The blade 30 continues on beneath the plate Hi3 and bearsagainst an eccentric screw 23 rising upward from the bottom plate I5.

By adjusting the relative position of the eccentric 23 the contacts 305and 306 are positioned at an adjustable distance from each other whenthe camera is in set position, as seen in Fig. 18, with the pawl I 34-latched in position as in Fig. 1.

A wire 3I0 is soldered to blade 3| and a wire 3| I is soldered to blade30. The two wires are passed through an insulating sheath 3I2 whichpasses forward to a position below and between the lenses where thewires 3I0 and 3H are connected to terminals 3I3 and 3I4 respectively,which pass through, but are insulated from, the bottom plate and are inposition to receive wires (not shown) leading to a flash bulb socket andmeans for applying voltage to the flash bulb when the contacts 305 and306 are broughttogether.

When it is desired to take a flashlight-picture appropriate standardbulb and battery accesseries are connected to terminals 3I3 and 3I4preparatory to flashing the bulb by closing contacts 305 and 303. Thefilm is exposed by pressing the button I33 (Fig. 10). Downward motion ofthe button I33 moves the release lever I6 through the action of the triplever 244. The tail and the bent-down tab 204 (Fig. 9) normally hold thelong switch blade-33 away from the eccentric screw 23 to a positionsufficiently far from blade 3i that the contacts 305 and 306 cannottouch regardless of the-position of other cooperating elements. Initialmovement of lever I 6, and hence of-tab 204, permits the blade 30 toyield to its inherent tension and come to rest in its active positionagainst eccentricscrew. 23 as shown in Fig. 18. Additional movement oflever I6 releases the primary latch pawl I34 which starts to 'rockcounterclockwise as de scribed previously. Very slight angular movementof pawl :34 from its normal set position moves the shoulder- I59sufliciently to permit blade 3I to yield toits inherent tensionand bringcontact 305 against contact 306'. Additionalimo ve- :accomplished solelypawl I3 positively times ters and the flashing of the bulb since both p-'tion mechanism which is not merit of pawl is i releases latch 1 andshutter blade I as described previously. The relationship between hook260 and shoulder I55 is preferably such that contact 305 is brought tobear against contact 3% approximately of a second before hook 268releases latch c for most flash bulbs. In this manner the flash bulb isignited and permitted to come to full intensity of light before theopening of the lens apertures. Adjustment of the position of eccentric23 by an attached slotted head 361 permits the second interval to bevaried as desired, Preferably the head 30? extends through the bottomplate E5 in order that such adjustment may be made from outside of thecamera, and may be calibrated with respect to a visible scale. Releaseof button l33 (Fig. by the operator after completion of the exposureprompts spring Iiil (Fig. l) to move the lever l6 and its tab 2%counterclockwise, returning the switch blade 33 to its inactive positionwith the contacts open. In this manner the circuit is rendered safe forthe operator to replace the flash bulb before resetting the shutter ifhe prefers without the danger of suffering severe burns from loadingbulbs in hot circuits.

After the latch 9 is released pawl 13% continues to the end of itsmovement and may be returned by the reset mechanism. The resettingoperation moves pawl I34 clockwise whereupon the shoulder W9 engages tab32 and moves blade 3! against its tension to the set position.

It will be noted that the spring tension of the short blade 3! on theprimary latch pawl its serves two useful purposes. The obvious purposeis to bring the contacts together with sufficient pressure for reliableelectrical contact when the primary latch pawl 134 permits the contactsto come together. The second and obscure purpose is to apply additionalstarting torque to the primary latch pawl i341. This is accomplished dueto the tab 32 pressing against the shoulder i551 and tending to rotatethe pawl Hi l in the same direction that it is forced by the spring [4,and this additional force increases the acceleration of the escapement,or, in other words, aids in overcoming the inertia of the escapementwhen the shutter is tripped. The torque supplied by the switch blade 3!is applied only until the contacts close which, as has been noted above,is approximately of a second before the shutter opens. Therefore theforce of the spring blade 3i has no effect on the shutter timing whichtakes place after latch 9 is released. During the shutter timing period,i. e., from the release of latch 9 to the release of latch ill, the onlyforce applied to the escapement mechanism is that of spring [4. It willbe observed that there is no possibility of error due to manualinterference with the timing of the switch since the timing is by thepawl [3d after the release lever i6 is operated. The primary latch theopening of the shuterations are entirely under its control.

I have time provided photo-flash synchronizain any manner affected bythe operation of the shutter release button. An operator who depressesthe button slowly will have exactly the same result as an operator whodepresses the button rapidly. It will .also be apparent that the use ofpigtails is eliminated both for simplicity of construction anduniformity and dependability of operation.

It is to be appreciated that the instant disclosure is with respect to astereoscopic camera having a pair of lenses. However, it will beapparent to any person skilled in the art that the shutter blades l and3 might have single apertures therethrough so located as to admit lightthrough a single set of lenses for the taking of ordinary photographs. Ido not intend that this patent should be limited to a stereoscopiccamera.

Having illustrated and described the preferred embodiment of the presentinvention, it should be apparent to those skilled in the art that thecombination and various portions of the combination are subject tomodification in detail and arrangement. Likewise, some one operation ofthe herein disclosed mechanism may be utilized without utilizing theothers in cameras omitting some of the refinements or the presentcamera, or in cameras having other types of mechanism for achievingsimilar functions. All such modifications in detail and arrangement ascome within the scope of the appended claims are considered to be a partof my invention.

I claim:

1. In a camera including a lens, a shutter movable from a lens obscuringposition to a lens exposing position, a shutter latch for holding saidshutter in its lens obscuring position, spring means operativelyconnected to said shutter to move said shutter to its lens exposingposition upon release of said shutter from said latch, a shutter latchpawl operatively releasing said shutter latch from said shutter, meansincluding a manually operable shutter release lever for actuating saidshutter latch pawl, and means including photoflash switch means forilluminating a scene in synchronization with the release of saidshutter; the improved photoflash switch means including two springcontact blades inherently self-biasing into closed position, means onsaid shutter latch pawl normally flexing one of said spring contactblades to an open position and releasing said one spring contact bladeto return to its closed position upon actuation of said shutter latchpawl to release said shutter latch, and means on said shutter releaselever normally flexing the other of said spring contact blades to anopen position away from the first mentioned shutter latch blade andreleasing said second spring contact blade to return to its closedposition upon manual actuation whereby accidental closing of thephotoflash switch is positively prevented until release of said shutteroccurs.

2. In a camera. comprising a lens, a shutter and a shutter releasemechanism including a manually operable shutter release lever and ashutter latch pawl controlled thereby, phcto'flash means including acircuit and a circuit controlling photoflash switch comprising a pair ofspring contact blades inherently self-biasing to spring together, meanson said release lever engageable with one of said spring contact bladesfor moving the same in a switch opening direction and positively holdingthe same beyond reach of the other spring contact blade when the cameralens is obsoured by the shutter, said release lever releasing said onespring contact blade to spring to circuitclcsing position when actuatedto effect release oi the shutter, adju" le means engageable by said onecontact blade to limit the extent of closing movement thereof whenreleased from said release lever, means on said shutter latch pawlengageable with the other of said spring 1 7 contact blades for movingthe same to a switch opening position, and an escapement mechanismconnected to said shutter latch pawl to efiect movement thereof at acontrolled rate of speed when released by said releas lever whereby saidother spring contact blade moves to circuit-closing position at acontrolled speed and said circuit is thereby closed at a timed intervalafter manual actuation of said release lever adjustably determined bythe setting of said adjustable means. 10

GORDON N. SmTI-I.

Number Name Date Grogin Aug. 4, 1936 Steiner Oct. 14, 1940 Riddell Sept.16, 1941 Schwarz Sept. 26, 1944 Sprague et a1. Nov. 14, 1944 Fuerst June13, 1950

